feat(frontend): implement unified design system with 17 reusable template components, skeleton loading states, and golden-ratio-based layouts

frontend/src/pages/Settings.tsx

@@ -38,7 +38,6 @@ import {
   useSortable,
 } from '@dnd-kit/sortable';
 import { CSS } from '@dnd-kit/utilities';
-import { useNavigate } from 'react-router-dom';
 import DashboardLayout from '../components/dashboard/DashboardLayout';
 import { useThemeMode } from '../contexts/ThemeContext';
 import { preferencesApi } from '../services/settings';